Increased x-ray conversion efficiency from ultra-high contrast, relativistic laser pulse irradiation of large aspect ratio, vertically aligned nanowires

R.C. HOLLINGER; V. KAYMAK; Y. WANG; A. CURTIS; V SHLYAPTSEV; M. G. CAPELUTO; A ROCKWOOD; C BARGSTEN; A. PUKHOV; S. WANG; J. J. ROCCA

Conferencia; Bulletin of the American Physical Society. 58th Annual Meeting of the APS Division of Plasma Physics, Volume 61, Number 18; 2016

Recent experiments at Colorado State University have shown that the effective trapping of clean, Joule-level fs laser pulses of relativistic intensity in arrays of high aspect ratio aligned nanowire creates multi-kev, near solid density, large scale (\textgreater 4um deep) plasmas. The drastically decreased radiative life time and increased hydrodynamic cooling time from these plasmas increases the x-ray conversion efficiency. We measured a record conversion efficiency of \textasciitilde 10{\%} into hv\textgreater 1KeV photons (2pi steradians), and of 0.3{\%} for hv\textgreater 6KeV. The experiments used Au and Ni nanowires of 55nm, 80nm and 100nm in diameter with 12{\%} of solid density irradiated by high contrast (\textgreater 1012) pulses of 60fs FWHM duration from a frequency doubled Ti:Sa laser at intensities of I=5x1019Wcm−2.We also present preliminary results on x-ray emission from Rhodium nanowires in the 19-22KeV range and demonstrate the potential of this picosecond X-ray source in flash radiography.